Does this work with negative numbers?

Yes — handles negatives correctly for modes 1 and 3. For mode 2 (X is what % of Y), if Y is negative the percentage will be negative, which is mathematically right but unusual.

Why is "decimal" useful?

Some contexts (Excel, statistics, programming) use decimals (0.225) instead of percentages (22.5%). Quick conversion for cross-tool work.

Percentage Calculator

Three-mode percentage tool — what is X% of Y, X is what % of Y, % change.

Result

25% of 200

As fraction0.2500 × 200
In money$50.00

How to use this calculator

Pick the mode that matches your question.
Type the two numbers — labels adapt based on mode.
Read the primary result + secondary breakdowns.

About this tool

Three percentage problems in one tool, because most "percentage calculators" only do one. Mode 1: classic "what is 15% of $80" (the answer is $12). Mode 2: "$45 is what % of $200" (22.5%). Mode 3: percentage change between two values — useful for "stock went from $50 to $73, what %?" (+46%). Mode 3 also shows the reverse change, which is NOT the same number — going from $73 back to $50 is a 32% decrease, not 46%, because the denominators differ.

Frequently asked

Because the denominator changes. $100 → $150 is +50% (gain ÷ original), but $150 → $100 is -33% (loss ÷ new starting point). Mathematically symmetric only at small values.